- Introduction
- Sub-project Status Update
- - External Projects Using LLVM 2.8
- - What's New in LLVM 2.8?
+ - External Projects Using LLVM 2.9
+ - What's New in LLVM 2.9?
- Installation Instructions
- Known Problems
- Additional Information
@@ -28,13 +28,11 @@
Written by the LLVM Team
-
@@ -45,7 +43,7 @@ Release Notes.
This document contains the release notes for the LLVM Compiler
-Infrastructure, release 2.8. Here we describe the status of LLVM, including
+Infrastructure, release 2.9. Here we describe the status of LLVM, including
major improvements from the previous release and significant known problems.
All LLVM releases may be downloaded from the LLVM releases web site.
@@ -62,17 +60,16 @@ current one. To see the release notes for a specific release, please see the
releases page.
-
+
+
-
-
-
-
Sub-project Status Update
@@ -91,7 +85,7 @@ Almost dead code.
-The LLVM 2.8 distribution currently consists of code from the core LLVM
+The LLVM 2.9 distribution currently consists of code from the core LLVM
repository (which roughly includes the LLVM optimizers, code generators
and supporting tools), the Clang repository and the llvm-gcc repository. In
addition to this code, the LLVM Project includes other sub-projects that are in
@@ -117,29 +111,10 @@ integrating with other development tools. Clang is considered a
production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
(32- and 64-bit), and for darwin-arm targets.
-
In the LLVM 2.8 time-frame, the Clang team has made many improvements:
+
In the LLVM 2.9 time-frame, the Clang team has made many improvements:
-
- - Clang C++ is now feature-complete with respect to the ISO C++ 1998 and 2003 standards.
- - Added support for Objective-C++.
- - Clang now uses LLVM-MC to directly generate object code and to parse inline assembly (on Darwin).
- - Introduced many new warnings, including
-Wmissing-field-initializers, -Wshadow, -Wno-protocol, -Wtautological-compare, -Wstrict-selector-match, -Wcast-align, -Wunused improvements, and greatly improved format-string checking.
- - Introduced the "libclang" library, a C interface to Clang intended to support IDE clients.
- - Added support for
#pragma GCC visibility, #pragma align, and others.
- - Added support for SSE, AVX, ARM NEON, and AltiVec.
- - Improved support for many Microsoft extensions.
- - Implemented support for blocks in C++.
- - Implemented precompiled headers for C++.
- - Improved abstract syntax trees to retain more accurate source information.
- - Added driver support for handling LLVM IR and bitcode files directly.
- - Major improvements to compiler correctness for exception handling.
- - Improved generated code quality in some areas:
-
- - Good code generation for X86-32 and X86-64 ABI handling.
- - Improved code generation for bit-fields, although important work remains.
-
-
-
+
@@ -156,8 +131,7 @@ production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
future!). The tool is very good at finding bugs that occur on specific
paths through code, such as on error conditions.
-
The LLVM 2.8 release fixes a number of bugs and slightly improves precision
- over 2.7, but there are no major new features in the release.
+
The LLVM 2.9 release...
@@ -168,6 +142,8 @@ production-quality compiler for C, Objective-C, C++ and Objective-C++ on x86
+NOTE: This should be written to be self-contained without referencing llvm-gcc.
+
DragonEgg is a port of llvm-gcc to
gcc-4.5. Unlike llvm-gcc, dragonegg in theory does not require any gcc-4.5
@@ -186,32 +162,24 @@ linux and darwin (darwin may need additional gcc patches).
-The 2.8 release has the following notable changes:
+The 2.9 release has the following notable changes:
-- The plugin loads faster due to exporting fewer symbols.
-- Additional vector operations such as addps256 are now supported.
-- Ada global variables with no initial value are no longer zero initialized,
-resulting in better optimization.
-- The '-fplugin-arg-dragonegg-enable-gcc-optzns' flag now runs all gcc
-optimizers, rather than just a handful.
-- Fortran programs using common variables now link correctly.
-- GNU OMP constructs no longer crash the compiler.
The VMKit project is an implementation of
a Java Virtual Machine (Java VM or JVM) that uses LLVM for static and
-just-in-time compilation. As of LLVM 2.8, VMKit now supports copying garbage
-collectors, and can be configured to use MMTk's copy mark-sweep garbage
-collector. In LLVM 2.8, the VMKit .NET VM is no longer being maintained.
+just-in-time compilation.
+
+UPDATE.
@@ -233,10 +201,11 @@ libgcc routines).
All of the code in the compiler-rt project is available under the standard LLVM
-License, a "BSD-style" license. New in LLVM 2.8, compiler_rt now supports
-soft floating point (for targets that don't have a real floating point unit),
-and includes an extensive testsuite for the "blocks" language feature and the
-blocks runtime included in compiler_rt.
+License, a "BSD-style" license.
+
+NEW: MIT License as well.
+
+New in LLVM 2.9, UPDATE
@@ -254,10 +223,13 @@ libraries in the larger LLVM Project, such as the Clang expression parser, the
LLVM disassembler and the LLVM JIT.
-LLDB is in early development and not included as part of the LLVM 2.8 release,
+LLDB is in early development and not included as part of the LLVM 2.9 release,
+UPDATE!
+
+
@@ -275,9 +247,11 @@ ground up to specifically target the forthcoming C++'0X standard and focus on
delivering great performance.
-As of the LLVM 2.8 release, libc++ is virtually feature complete, but would
+As of the LLVM 2.9 release, UPDATE!
+
+
@@ -298,31 +272,14 @@ states. This allows it to construct testcases that lead to faults and can even
be used to verify some algorithms.
-Although KLEE does not have any major new features as of 2.8, we have made
-various minor improvements, particular to ease development:
-
- - Added support for LLVM 2.8. KLEE currently maintains compatibility with
- LLVM 2.6, 2.7, and 2.8.
- - Added a buildbot for 2.6, 2.7, and trunk. A 2.8 buildbot will be coming
- soon following release.
- - Fixed many C++ code issues to allow building with Clang++. Mostly
- complete, except for the version of MiniSAT which is inside the KLEE STP
- version.
- - Improved support for building with separate source and build
- directories.
- - Added support for "long double" on x86.
- - Initial work on KLEE support for using 'lit' test runner instead of
- DejaGNU.
- - Added configure support for using an external version of
- STP.
-
+UPDATE!
@@ -330,264 +287,15 @@ various minor improvements, particular to ease development:
An exciting aspect of LLVM is that it is used as an enabling technology for
a lot of other language and tools projects. This section lists some of the
- projects that have already been updated to work with LLVM 2.8.
+ projects that have already been updated to work with LLVM 2.9.
-
-
-
-
-
-TCE is a toolset for designing
-application-specific processors (ASP) based on the Transport triggered
-architecture (TTA). The toolset provides a complete co-design flow from C/C++
-programs down to synthesizable VHDL and parallel program binaries. Processor
-customization points include the register files, function units, supported
-operations, and the interconnection network.
-
-
TCE uses llvm-gcc/Clang and LLVM for C/C++ language support, target
-independent optimizations and also for parts of code generation. It generates
-new LLVM-based code generators "on the fly" for the designed TTA processors and
-loads them in to the compiler backend as runtime libraries to avoid per-target
-recompilation of larger parts of the compiler chain.
-
-
-
-Horizon is a bytecode
-language and compiler written on top of LLVM, intended for producing
-single-address-space managed code operating systems that
-run faster than the equivalent multiple-address-space C systems.
-More in-depth blurb is available on the wiki.
-
-
-
-Clam AntiVirus is an open source (GPL)
-anti-virus toolkit for UNIX, designed especially for e-mail scanning on mail
-gateways. Since version 0.96 it has bytecode
-signatures that allow writing detections for complex malware. It
-uses LLVM's JIT to speed up the execution of bytecode on
-X86, X86-64, PPC32/64, falling back to its own interpreter otherwise.
-The git version was updated to work with LLVM 2.8.
-
-
-
The
-ClamAV bytecode compiler uses Clang and LLVM to compile a C-like
-language, insert runtime checks, and generate ClamAV bytecode.
-
-
-
-Pure
-is an algebraic/functional
-programming language based on term rewriting. Programs are collections
-of equations which are used to evaluate expressions in a symbolic
-fashion. Pure offers dynamic typing, eager and lazy evaluation, lexical
-closures, a hygienic macro system (also based on term rewriting),
-built-in list and matrix support (including list and matrix
-comprehensions) and an easy-to-use C interface. The interpreter uses
-LLVM as a backend to JIT-compile Pure programs to fast native code.
-
-
Pure versions 0.44 and later have been tested and are known to work with
-LLVM 2.8 (and continue to work with older LLVM releases >= 2.5).
-
-
-
-GHC is an open source,
-state-of-the-art programming suite for
-Haskell, a standard lazy functional programming language. It includes
-an optimizing static compiler generating good code for a variety of
-platforms, together with an interactive system for convenient, quick
-development.
-
-
In addition to the existing C and native code generators, GHC 7.0 now
-supports an LLVM
-code generator. GHC supports LLVM 2.7 and later.
-
-
-
-Clay is a new systems programming
-language that is specifically designed for generic programming. It makes
-generic programming very concise thanks to whole program type propagation. It
-uses LLVM as its backend.
-
-
-
-llvm-py has been updated to work
-with LLVM 2.8. llvm-py provides Python bindings for LLVM, allowing you to write a
-compiler backend or a VM in Python.
-
-
-
-FAUST is a compiled language for real-time
-audio signal processing. The name FAUST stands for Functional AUdio STream. Its
-programming model combines two approaches: functional programming and block
-diagram composition. In addition with the C, C++, JAVA output formats, the
-Faust compiler can now generate LLVM bitcode, and works with LLVM 2.7 and
-2.8.
-
-
-
Jade
-(Just-in-time Adaptive Decoder Engine) is a generic video decoder engine using
-LLVM for just-in-time compilation of video decoder configurations. Those
-configurations are designed by MPEG Reconfigurable Video Coding (RVC) committee.
-MPEG RVC standard is built on a stream-based dataflow representation of
-decoders. It is composed of a standard library of coding tools written in
-RVC-CAL language and a dataflow configuration — block diagram —
-of a decoder.
-
-
Jade project is hosted as part of the Open
-RVC-CAL Compiler and requires it to translate the RVC-CAL standard library
-of video coding tools into an LLVM assembly code.
-
-
-
Neko LLVM JIT
-replaces the standard Neko JIT with an LLVM-based implementation. While not
-fully complete, it is already providing a 1.5x speedup on 64-bit systems.
-Neko LLVM JIT requires LLVM 2.8 or later.
-
-
-
-Crack aims to provide
-the ease of development of a scripting language with the performance of a
-compiled language. The language derives concepts from C++, Java and Python,
-incorporating object-oriented programming, operator overloading and strong
-typing. Crack 0.2 works with LLVM 2.7, and the forthcoming Crack 0.2.1 release
-builds on LLVM 2.8.
-
-
-
-DTMC provides support for
-Transactional Memory, which is an easy-to-use and efficient way to synchronize
-accesses to shared memory. Transactions can contain normal C/C++ code (e.g.,
-__transaction { list.remove(x); x.refCount--; }) and will be executed
-virtually atomically and isolated from other transactions.
-
-
-
-Kai (Japanese 会 for
-meeting/gathering) is an experimental interpreter that provides a highly
-extensible runtime environment and explicit control over the compilation
-process. Programs are defined using nested symbolic expressions, which are all
-parsed into first-class values with minimal intrinsic semantics. Kai can
-generate optimised code at run-time (using LLVM) in order to exploit the nature
-of the underlying hardware and to integrate with external software libraries.
-It is a unique exploration into world of dynamic code compilation, and the
-interaction between high level and low level semantics.
-
-
-
-OSL is a shading
-language designed for use in physically based renderers and in particular
-production rendering. By using LLVM instead of the interpreter, it was able to
-meet its performance goals (>= C-code) while retaining the benefits of
-runtime specialization and a portable high-level language.
-
-
-
-
LLVM 2.8 includes several major new capabilities:
+
LLVM 2.9 includes several major new capabilities:
-- As mentioned above, libc++ and LLDB are major new additions to the LLVM collective.
-- LLVM 2.8 now has pretty decent support for debugging optimized code. You
- should be able to reliably get debug info for function arguments, assuming
- that the value is actually available where you have stopped.
-- A new 'llvm-diff' tool is available that does a semantic diff of .ll
- files.
-- The MC subproject has made major progress in this release.
- Direct .o file writing support for darwin/x86[-64] is now reliable and
- support for other targets and object file formats are in progress.
-- The memcpy, memmove, and memset
- intrinsics now take address space qualified pointers and a bit to indicate
- whether the transfer is "volatile" or not.
-
-- Per-instruction debug info metadata is much faster and uses less memory by
- using the new DebugLoc class.
-- LLVM IR now has a more formalized concept of "trap values", which allow the optimizer
- to optimize more aggressively in the presence of undefined behavior, while
- still producing predictable results.
-- LLVM IR now supports two new linkage
- types (linker_private_weak and linker_private_weak_def_auto) which map
- onto some obscure MachO concepts.
@@ -662,30 +347,7 @@ expose new optimization opportunities:
release includes a few major enhancements and additions to the optimizers:
-- As mentioned above, the optimizer now has support for updating debug
- information as it goes. A key aspect of this is the new llvm.dbg.value
- intrinsic. This intrinsic represents debug info for variables that are
- promoted to SSA values (typically by mem2reg or the -scalarrepl passes).
-
-- The JumpThreading pass is now much more aggressive about implied value
- relations, allowing it to thread conditions like "a == 4" when a is known to
- be 13 in one of the predecessors of a block. It does this in conjunction
- with the new LazyValueInfo analysis pass.
-- The new RegionInfo analysis pass identifies single-entry single-exit regions
- in the CFG. You can play with it with the "opt -regions -analyze" or
- "opt -view-regions" commands.
-- The loop optimizer has significantly improved strength reduction and analysis
- capabilities. Notably it is able to build on the trap value and signed
- integer overflow information to optimize <= and >= loops.
-- The CallGraphSCCPassManager now has some basic support for iterating within
- an SCC when a optimizer devirtualizes a function call. This allows inlining
- through indirect call sites that are devirtualized by store-load forwarding
- and other optimizations.
-- The new -loweratomic pass is available
- to lower atomic instructions into their non-atomic form. This can be useful
- to optimize generic code that expects to run in a single-threaded
- environment.
+TBAA.
-
-- The -fast-isel instruction selection path (used at -O0 on X86) was rewritten
- to work bottom-up on basic blocks instead of top down. This makes it
- slightly faster (because the MachineDCE pass is not needed any longer) and
- allows it to generate better code in some cases.
-
+FastISel for ARM.
@@ -816,42 +410,6 @@ it run faster:
-- The X86 backend now supports holding X87 floating point stack values
- in registers across basic blocks, dramatically improving performance of code
- that uses long double, and when targeting CPUs that don't support SSE.
-
-- The X86 backend now uses a SSEDomainFix pass to optimize SSE operations. On
- Nehalem ("Core i7") and newer CPUs there is a 2 cycle latency penalty on
- using a register in a different domain than where it was defined. This pass
- optimizes away these stalls.
-
-- The X86 backend now promotes 16-bit integer operations to 32-bits when
- possible. This avoids 0x66 prefixes, which are slow on some
- microarchitectures and bloat the code on all of them.
-
-- The X86 backend now supports the Microsoft "thiscall" calling convention,
- and a calling convention to support
- ghc.
-
-- The X86 backend supports a new "llvm.x86.int" intrinsic, which maps onto
- the X86 "int $42" and "int3" instructions.
-
-- At the IR level, the <2 x float> datatype is now promoted and passed
- around as a <4 x float> instead of being passed and returned as an MMX
- vector. If you have a frontend that uses this, please pass and return a
- <2 x i32> instead (using bitcasts).
-
-- When printing .s files in verbose assembly mode (the default for clang -S),
- the X86 backend now decodes X86 shuffle instructions and prints human
- readable comments after the most inscrutable of them, e.g.:
-
-
- insertps $113, %xmm3, %xmm0 # xmm0 = zero,xmm0[1,2],xmm3[1]
- unpcklps %xmm1, %xmm0 # xmm0 = xmm0[0],xmm1[0],xmm0[1],xmm1[1]
- pshufd $1, %xmm1, %xmm1 # xmm1 = xmm1[1,0,0,0]
-
-
-
@@ -866,72 +424,6 @@ it run faster:
-- The ARM backend now optimizes tail calls into jumps.
-- Scheduling is improved through the new list-hybrid scheduler as well
- as through better modeling of structural hazards.
-- Half float instructions are now
- supported.
-- NEON support has been improved to model instructions which operate onto
- multiple consecutive registers more aggressively. This avoids lots of
- extraneous register copies.
-- The ARM backend now uses a new "ARMGlobalMerge" pass, which merges several
- global variables into one, saving extra address computation (all the global
- variables can be accessed via same base address) and potentially reducing
- register pressure.
-
-- The ARM backend has received many minor improvements and tweaks which lead
- to substantially better performance in a wide range of different scenarios.
-
-
-- The ARM NEON intrinsics have been substantially reworked to reduce
- redundancy and improve code generation. Some of the major changes are:
-
- -
- All of the NEON load and store intrinsics (llvm.arm.neon.vld* and
- llvm.arm.neon.vst*) take an extra parameter to specify the alignment in bytes
- of the memory being accessed.
-
- -
- The llvm.arm.neon.vaba intrinsic (vector absolute difference and
- accumulate) has been removed. This operation is now represented using
- the llvm.arm.neon.vabd intrinsic (vector absolute difference) followed by a
- vector add.
-
- -
- The llvm.arm.neon.vabdl and llvm.arm.neon.vabal intrinsics (lengthening
- vector absolute difference with and without accumulation) have been removed.
- They are represented using the llvm.arm.neon.vabd intrinsic (vector absolute
- difference) followed by a vector zero-extend operation, and for vabal,
- a vector add.
-
- -
- The llvm.arm.neon.vmovn intrinsic has been removed. Calls of this intrinsic
- are now replaced by vector truncate operations.
-
- -
- The llvm.arm.neon.vmovls and llvm.arm.neon.vmovlu intrinsics have been
- removed. They are now represented as vector sign-extend (vmovls) and
- zero-extend (vmovlu) operations.
-
- -
- The llvm.arm.neon.vaddl*, llvm.arm.neon.vaddw*, llvm.arm.neon.vsubl*, and
- llvm.arm.neon.vsubw* intrinsics (lengthening vector add and subtract) have
- been removed. They are replaced by vector add and vector subtract operations
- where one (vaddw, vsubw) or both (vaddl, vsubl) of the operands are either
- sign-extended or zero-extended.
-
- -
- The llvm.arm.neon.vmulls, llvm.arm.neon.vmullu, llvm.arm.neon.vmlal*, and
- llvm.arm.neon.vmlsl* intrinsics (lengthening vector multiply with and without
- accumulation and subtraction) have been removed. These operations are now
- represented as vector multiplications where the operands are either
- sign-extended or zero-extended, followed by a vector add for vmlal or a
- vector subtract for vmlsl. Note that the polynomial vector multiply
- intrinsic, llvm.arm.neon.vmullp, remains unchanged.
-
-
-
-
@@ -944,29 +436,10 @@ it run faster:
If you're already an LLVM user or developer with out-of-tree changes based
-on LLVM 2.7, this section lists some "gotchas" that you may run into upgrading
+on LLVM 2.8, this section lists some "gotchas" that you may run into upgrading
from the previous release.
-- The build configuration machinery changed the output directory names. It
- wasn't clear to many people that a "Release-Asserts" build was a release build
- without asserts. To make this more clear, "Release" does not include
- assertions and "Release+Asserts" does (likewise, "Debug" and
- "Debug+Asserts").
-- The MSIL Backend was removed, it was unsupported and broken.
-- The ABCD, SSI, and SCCVN passes were removed. These were not fully
- functional and their behavior has been or will be subsumed by the
- LazyValueInfo pass.
-- The LLVM IR 'Union' feature was removed. While this is a desirable feature
- for LLVM IR to support, the existing implementation was half baked and
- barely useful. We'd really like anyone interested to resurrect the work and
- finish it for a future release.
-- If you're used to reading .ll files, you'll probably notice that .ll file
- dumps don't produce #uses comments anymore. To get them, run a .bc file
- through "llvm-dis --show-annotations".
-- Target triples are now stored in a normalized form, and all inputs from
- humans are expected to be normalized by Triple::normalize before being
- stored in a module triple or passed to another library.
@@ -974,72 +447,6 @@ from the previous release.
In addition, many APIs have changed in this release. Some of the major LLVM
API changes are:
-- LLVM 2.8 changes the internal order of operands in InvokeInst
- and CallInst.
- To be portable across releases, please use the CallSite class and the
- high-level accessors, such as getCalledValue and
- setUnwindDest.
-
--
- You can no longer pass use_iterators directly to cast<> (and similar),
- because these routines tend to perform costly dereference operations more
- than once. You have to dereference the iterators yourself and pass them in.
-
--
- llvm.memcpy.*, llvm.memset.*, llvm.memmove.* intrinsics take an extra
- parameter now ("i1 isVolatile"), totaling 5 parameters, and the pointer
- operands are now address-space qualified.
- If you were creating these intrinsic calls and prototypes yourself (as opposed
- to using Intrinsic::getDeclaration), you can use
- UpgradeIntrinsicFunction/UpgradeIntrinsicCall to be portable across releases.
-
--
- SetCurrentDebugLocation takes a DebugLoc now instead of a MDNode.
- Change your code to use
- SetCurrentDebugLocation(DebugLoc::getFromDILocation(...)).
-
--
- The RegisterPass and RegisterAnalysisGroup templates are
- considered deprecated, but continue to function in LLVM 2.8. Clients are
- strongly advised to use the upcoming INITIALIZE_PASS() and
- INITIALIZE_AG_PASS() macros instead.
-
--
- The constructor for the Triple class no longer tries to understand odd triple
- specifications. Frontends should ensure that they only pass valid triples to
- LLVM. The Triple::normalize utility method has been added to help front-ends
- deal with funky triples.
-
--
- The signature of the GCMetadataPrinter::finishAssembly virtual
- function changed: the raw_ostream and MCAsmInfo arguments
- were dropped. GC plugins which compute stack maps must be updated to avoid
- having the old definition overload the new signature.
-
--
- The signature of MemoryBuffer::getMemBuffer changed. Unfortunately
- calls intended for the old version still compile, but will not work correctly,
- leading to a confusing error about an invalid header in the bitcode.
-
-
--
- Some APIs were renamed:
-
- - llvm_report_error -> report_fatal_error
- - llvm_install_error_handler -> install_fatal_error_handler
- - llvm::DwarfExceptionHandling -> llvm::JITExceptionHandling
- - VISIBILITY_HIDDEN -> LLVM_LIBRARY_VISIBILITY
-
-
-
--
- Some public headers were renamed:
-
- - llvm/Assembly/AsmAnnotationWriter.h was renamed
- to llvm/Assembly/AssemblyAnnotationWriter.h
-
-
@@ -1057,30 +464,6 @@ mainline, but may also impact users who leverage the LLVM build infrastructure
or are interested in LLVM qualification.
- - The default for make check is now to use
- the lit testing tool, which is
- part of LLVM itself. You can use lit directly as well, or use
- the llvm-lit tool which is created as part of a Makefile or CMake
- build (and knows how to find the appropriate tools). See the lit
- documentation and the blog
- post, and PR5217
- for more information.
-
- - The LLVM test-suite infrastructure has a new "simple" test format
- (make TEST=simple). The new format is intended to require only a
- compiler and not a full set of LLVM tools. This makes it useful for testing
- released compilers, for running the test suite with other compilers (for
- performance comparisons), and makes sure that we are testing the compiler as
- users would see it. The new format is also designed to work using reference
- outputs instead of comparison to a baseline compiler, which makes it run much
- faster and makes it less system dependent.
-
- - Significant progress has been made on a new interface to running the
- LLVM test-suite (aka the LLVM "nightly tests") using
- the LNT infrastructure. The LNT
- interface to the test-suite brings significantly improved reporting
- capabilities for monitoring the correctness and generated code quality
- produced by LLVM over time.
@@ -1114,10 +497,11 @@ components, please contact us on the LLVMdev list.
-- The Alpha, Blackfin, CellSPU, MicroBlaze, MSP430, MIPS, SystemZ
+
- The Alpha, Blackfin, CellSPU, MicroBlaze, MSP430, MIPS, PTX, SystemZ
and XCore backends are experimental.
- llc "-filetype=obj" is experimental on all targets
- other than darwin-i386 and darwin-x86_64.
+ other than darwin-i386 and darwin-x86_64. FIXME: Not true on ELF anymore?
+
@@ -17,8 +17,8 @@